This invention relates to devices which allow indication of temporal changes in various forms other than and including the display of time, and specifically to changes in the Biorhythm cycles of an individual. Bio-rhythms for individuals are calculated starting from an individual's date of birth and are represented by three cycles which oscillate between positive or high periods of activity and negative or low periods of activity where in between is a critical line which defines the border between these two phases. Firstly, the intelligence cycle which lasts for thirty three days involves the intensity and acuteness to which the thought or mental powers of an individual are used. Secondly, the emotional cycle which lasts for twenty eight days relates to the mood or sensitivity that an individual experiences. Thirdly, the physical cycle which lasts for twenty three days relates to the amount of physical body strength an individual feels comfortable expending. Research shows that there is a considerable amount of significance to changes in these three cycles particularly when any of them crosses the critical line, and even more so when more than one cross the critical line at the same time. This has been taken seriously to the extent that various governments have funded research on Bio-rhythms especially as they relate to high risk situations as in aeronautics safety.